Thousands of antibodies are produced every year by commercial companies. However, many of these antibodies are known to be poorly characterized and suboptimal across applications. Polyclonal antibodies lack the reproducibility of monoclonal antibodies. The production of monoclonal antibodies is expensive and may take months. Even after production, a monoclonal antibody may not be specific for the target of interest, may not work in the needed assay, or could not be used in combination with other antibodies due to competition for overlapping binding domains. As such, the high cost associated with producing even small quantities of monoclonal antibodies represents a large barrier to cost-effective reagents for proteomic technology research and clinical adaptation. This project utilizes a new tool, massively parallel selection of DNA aptamers to rapidly identify high-affinity ligands to hundreds or even thousands of protein targets simultaneously. In this Phase II SBIR contract, we will utilize our platform to select aptamers to at least 75 important cancer biomarker proteins and characterize the new reagents for affinity and specificity. We will also demonstrate their performance in a number of common applications. The developed reagents will have tremendous value to the research community and potential to alleviate human suffering due to cancer.